1. Field of the Invention
This invention relates to a crop blower, particularly adapted to replace a conventional bat reel on a combine harvester.
2. Description of Related Art
Crop blowers, also known as pneumatic header attachments or air reels, have been developed to replace conventional bat reels on combine harvesters to improve the cutting action and the crop yield. Some earlier types of crop blowers included a blower mounted to the rear of the combine crop cutting header near the power shaft. The devices were conventionally driven by belts from the power shaft. Typically, a flexible air tube was employed to take air from the blower and forward to a manifold running across and in front of the crop cutting knife. The manifold usually had numerous downspouts which delivered air through nozzles at high speed to direct the crop back into the cutter and then into the auger conveyor. Considerable power was required to provide a sufficient volume and pressure of air to properly direct the crop.
However, some crops or crop conditions required much higher forces than could be obtained from crop blowers of the type described above. For this reason, crop blowers were developed with separate fans, one at each end of the table. However, those apparatuses were relatively expensive, consumed a lot of power and increased the force applied to the crops by only about 35%.
Tangential flow fans, or vortex fans, have been employed in crop blowers as seen for example in U.S. Pat. No. 3,828,531 to Quick. While Quick appears to show a viable means of providing a high volume current of air across the combine header, in fact the apparatus disclosed cannot be employed on many combine harvesters which often have a width exceeding 9 meters. It is simply not feasible to support a 9 meter long fan by bearings located only at the ends of the fan as Quick would suggest.
One solution to this problem is to employ a series of separate fans connected together end to end across the width of the combine harvester as disclosed in U.S. Pat. No. 4,914,896 to M. Roy Gullickson. In this way, intermediate bearing supports are provided for the fan means across the width of the harvester. This patent discloses the use of both conventional centrifugal fans as well as tangential flow or cross-flow fans. The use of a series of separate fans extending across the width of the harvester permits a high volume of air to be applied to the crop, but appreciably reduces the power requirements of the apparatus.
However, while providing significantly improved operation when compared with conventional apparatuses, the invention described in this patent requires relatively heavy structural members to support the tangential flow fans. The resulting apparatus is heavy and difficult and expensive to manufacture. Thus the marketability and acceptability of the product to farmers was somewhat limited.